Gmail 2.0 for iOS features a flatter UI that more closely resembles the revamped look of other Google properties and services.

By most accounts, the launch of Gmail 2.0 went much smoother than the original last year. Then, Google pulled the app from Apple's App Store within minutes, issued an apology and admitted it had "messed up" by shipping a flawed version.

Most reviews of Gmail 2.0 were positive -- Wired said it "rocks,"ReadWrite noted it "doesn't suck anymore" -- but a few chastised the upgrade for still seeming too much like the Web edition. The Verge called it "a frustratingly mixed bag" and "ultimately flawed."

Besides the new support for multiple accounts, Gmail 2.0 also beefed up integration with Google+, the company's Facebook competitor; sported a flatter UI (user interface) akin to other Google designs; and offered in-app RSVPs to Google Calendar invitations.